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[Example] StudentScore.sol

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.1;

contract StudentScore {
    mapping (string => uint) scores;
    string[] names;

    function addScore(string memory name, uint256 score) public {
        scores[name] = score; // mapping declare
        names.push(name);
    }

    function getScore(string memory name) public view returns (uint256) {
        return scores[name];
    }

    function deleteScore() public {
        while (names.length >0 ) {
            delete scores[names[names.length-1]]; // delete the name which is the last of the names Array.
            names.pop();
        }
    }

}